This invention relates to a method for fermentation of a stockbreeding waste, especially fowl droppings. The product according to the fermentation method is usable as a fertilizer, a soil improver, a medium for fermentation of the stockbreeding wastes etc.
Conventional fermented fowl droppings are produced by admixing sawdust, chaff, etc. with fowl droppings, adjusting water content of the resulting mixture, fermenting a compost pile while the pile is sometimes turned over, and finally drying the pile. The fermented fowl droppings are used as manure, etc. but the effect is not fully satisfactory, because of insufficiency as the culture medium.
On the other hand, there are known granules obtained by mixing synthesized wollastonite and concentrated sulfuric acid to fowl droppings and condensing and granulating the mixture (see Japanese Patent Publication No. 3006/80). The granules are hereinafter referred to as "SK-treated material". Further, the treatment method is referred to as "SK treatment". SK-treated material is free from the bad smell of fowl droppings and is in the dried state, and thus usable as an organic fertilizer containing calcium sulfate and Si.
Synthesized wollastonite used in the present invention is raw material of ceramic products, and has been developed, manufactured and sold by Onoda Cement Co., Ltd., Japan. Its composition, properties, etc. are disclosed in Japanese Patent Publication Nos. 19321/67 and 3246/72. Further, the preparation method of calcium silicate type silica sol and gel obtained by treating synthesized wollastonite with concentrated sulfuric acid, etc. is disclosed in Japanese Patent Publication No. 23764/80. (The calcium silicate type silica sol is denoted as "active silicic acid sol" hereinafter). The synthesized wollastonite is a mixture having the composition shown in the following Table 1.
TABLE 1 ______________________________________ Com- po- To- sition SiO.sub.2 Al.sub.2 O.sub.3 Fe.sub.2 O.sub.3 CaO MgO Na.sub.2 O K.sub.2 O tal ______________________________________ Weight 53.0 2.8 0.30 43.0 0.5 0.3 0.8 100.7 ______________________________________
The crystal structure of the main components is that of Ca ion combining Si.sub.3 O.sub.9 wherein three SiO.sub.4 tetrahedrous are combined.
Japanese Patent Publication No. 3006/80 discloses that porous condensed granular materials are formed is the SK treated material. Thereafter, the inventors have discovered the following new findings. That is, where the porous condensed granular materials are formed, microorganisms such as a thermophilic microorganism, an acid resistant microorganism, etc., enzymes and organic substances, which survived a severe environment of heat (40.degree.-60.degree. C.) owing to neutralization reaction of synthetic wollastonite with concentrated sulphuric acid, exist as a guest in the porous condensed granular materials as a host. Almost all the infectious microbes, putrefaction-causing microorganisms and pathogenic microorganisms, pests, seeds of weeds, etc. in the fowl droppings have been perished due to heat of neutralization reaction of synthetic wollastonite with conc. H.sub.2 SO.sub.4. Thus, SK treated material offers suitable environment such as moisture and pH for microorganisms existing in the porous condensed granular materials. Further, parts of starch substance in the fowl droppings have been decomposed and saccharificated by concentrated sulfuric acid and undigested substances in the fowl droppings have also been decomposed, and thus, SK treated material is abundant in nutrients for microorganisms. Furthermore, active silicic acid sol formed in SK-treatment is extremely fine granules and has porous, agglomerated granule having a high surface active property, and thus seems to attribute the selectivity of multiplication and metabolism of microorganisms by inhibiting contamination of infectious microbes. Moreover, the porous agglomerated granules are uniformly dispersed in SK treated material without uneven distribution, and due to their adiabatic property, generation of excess fermentative heat and subsequent carbonization of the organic substances are avoided. That is, fertilizer components which contain nitrogen, phosphoric acid and/or potassium and serve for growth of plants, and other organic substances which microorganisms can metabolize are prevented from carbonization or vanishing. Thus, the SK-treated material is a medium provided with most suitable environment for microorganisms.
Now, a method for fermentation of SK-treated material has been found out to obtain a product usable as excellent fertilizer, soil improver and fermenting medium for stockbreeding wastes.